Magneto generator



Aug. 17, 1937. w. J. SPENGLER El AL MAGNETO GENERATOR Filed May 9, 1936 5 SheetsSheet l INVENTOR.

MIT/Lesa Aug. 17, 1937. w. .1. SPENGLER ET AL 2,090,553

MAGNETO GENERATOR Filed May 9, 1936 5 Sheets-Sheet 2 INVENTOR. waier- J 5 601170660: gt-liaaeflw formu- Aug. 17, 1937.

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M. BY W A ORNEY.

1937. w. J. SPENGL'ER Er AL. 2,090,553

MAGNETO GENERATO R Filed May 9, 19:56 5 Sheets-Sheet 4 Aug. 17, 1937. w. J. SPENGLER ET AL 2,090,558

MAGNETO GENERATO R Filed May 9, 1936 5 Sheets-Sheet 5 wantedflmwlgflumzt V IN VENTOR.

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Patented Aug. 17, 1937 UNITED STATES MAGNETO GENERATOR Walter J Spengler and Gustave D. Cerf, Sidney,

N. Y., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application May 9, 1936, Serial No. 78,864

11 Claims.

. The present invention relates to a magneto generator and more particularly to an oscillating type of magneto adapted to supply ignition current for internal combustion engines.

In certain slow speed heavy duty engine installations, it has been found difllcult to use a magneto of conventional type due to the low output at such slow speeds. It has, therefore, been necessary to use comparatively large and expensive designs of magnetos,.and since it requires a large amount of energy to crank such large and heavy engines fast enough to operate a conventional magneto, impulse couplings in the drives are necessary, which couplings are somewhat expensive and subject to wear.

It has heretofore been suggested for installations of this type to use a magneto which is caused to oscillate in timed relation with the rotation of the engine, the oscillations consisting of a backward or winding-up swing of the rotor against a suitable spring, at the end of which swing the rotor is released so as to be rapidly rotion such as about 500 R. P. M., and it has been found that the oscillating magnetos as heretofore employed fall off rapidly in eificiency as the speed is increased above 250 to 300 R. P. M., and become quite unsatisfactory for higher engine speeds. Applicants have found by careful analysis of the operation that this loss of efliciency magneto which is simple and economical in construction and reliable and efilcient in operation.

It is another object to provide such a device which maintains uniform high efficiency at comparatively high operating speeds.

It is a further object to provide such a device in which the ignition current generated is free from interference by previously generated reverse currents.

Another object is to provide such a device in which the generation of reverse currents during the backward or wind-up swing of the magneto is effectively prevented.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a perspective view of a magneto embodying a preferred form of the invention;

Fig. 2 is a side view thereof partly in vertica section;

Fig. 3 is an end view of the driving end of the same with the drive housing cover removed, certain of the parts being broken away for the sake of clarity;

Fig. 4 1s an end view of the breaker end of the magneto, the cover of the breaker being removed to permit inspection;

Fig. 5 is a semi-diagrammatic illustration of the working parts and electrical circuits of the device; and

Fig. 6 is a graphical representation of the operation of the breaker mechanism and of the primary currents generated by the improved device in contrast to the results secured in operation of a conventional oscillating magneto.

Referring first to. Fig. l of the drawings, there is illustrated a magneto having a frame I provided with a cover 2 from which emerges the insulated high tension output cable 3. A breaker mechanism housing 4 is mounted at one end of the frame i and a drive housing 5 is mounted on the other end in any suitable manner and is closed by a cover plate 6.

In Fig. 3 the cover plate 6 of the drive housing is removed, exposing an actuating slide member pivoted thereon as illustrated at M and provided with a shoulder l5 adapted to engage a projection IS on a driven element 11 suitably keyed to a rotor shaft I 8. The member I 3 is urged into the path of the projection l6 by suitable means such as a spring I9 whereby motion of the slide 1 to the right in Fig. 3 causes the shoulder I5 to member l3 whereby said actuating member is cammed down against the force of the spring l9 until the shoulder i 5 is moved out of engagement with the projection IS. The position of the disengaging member 2| is manually adjustable by suitable means such as a lever 24 pivoted at 25 to the drive housing and provided with locking means 26 (Fig. 1). The lower end 21 of lever 24 is arranged to engage in a recess 28 in the member 2| whereby the adjustment of the lever determines the longitudinal position of the element The disengaging member 2| is provided with an opening'30 receiving the end of guide bar H and serves as an abutment for the return spring 9.

Referring now to Fig. 2 of the drawings, it

will be seen that the rotor shaft i8 is mounted in suitable bearings 29 and 3| in the drive housing 5 and breaker housing l respectively, which housings are suitably attached to the magneto frame 5 as by means of studs 32 and 33 respectively. A

magnetic rotor 34 is suitably fixed on the shaft H8 in position to cooperate with fixed pole members 35 in the magneto frame which are arranged to conduct the flux from the rotor through the core 36 of an induction coil 31 (Fig. 5) whereby 5 cuirrents may be generated in the "primary of said col. i

Means are provided for returning the rotor to its normal position after being displaced by the action of the slide 7, in the form of a' helical A40 spring 38 housed within the driven element Ii keyed on the rotor shaft. One end of the spring 38 is suitably anchoredto said driven element, and the opposite end isgprovided with a suitable fixed anchorage suchj'as' a,post' 39 fixed in the drive housing 5. The

the spring 38 is wound up during the backward I rotation of the element l1, and when said element is released by the action of. the disengaging -memheld in its normal position by suitablemeans such as a compression spring 43 bearing thereon and enclosed by a cup member 44.

The primary current generated in coil 31 is conducted as by means of a lead 45- (Fig. 2) to a breaker meachanism comprising a stationary 55 contact 46 (Figs. 4 and 5) and a movable contact 41 mounted on a leaf spring element 48 anchored at 49 in the breaker housing and grounded thereto.

A cam 5| is adapted to engage a follower 52 7 mounted on a spring 53 also anchored at 49, the follower 52 being arranged to engage the spring 48 and move the contact 4! out of engagement with the fixed contact 46 when the high part 54 of the cam 5| engages the follower 52. 7 According tothe present invention, the cam 5| ngement is such that aooopss is pivotally mounted on the end of the rotor shaft i8 as by means of a stud 55 (Fig. 2) which carries a bearing member 56 for said cam. A coupling member 51 is suitably keyed on the end of the rotor shaft i8 as illustrated at 58 and is retained thereon by means of a flange 59 of the bearing member 56 which is clamped against the coupling member when the stud 55 is screwed into the rotor shaft N. The coupling member 51 is provided with shoulders 6| and 62 (Fig. 4) arranged to engage and move the cam member 5| with the coupling member. A predetermined amount of lost motion represented by the spaces 63 and 64 is provided between the cam member 5| and the shoulders 6| and 62 whereby the cam member will 'not be actuated by the coupling member 51 until this lost motion is taken up;

, Suitable means is provided for yieldably holding the cam 5| in either its operative or inoperative positions when it is not being actuated by the coupling member 57. As here shown, this means is in the form of a yieldable detent B5 are ranged to engage one or the other of a pair of depressions 65 and 61 in the end of said cam member, the detent 65 being arranged to engage until the engagement of the inclined surface 22 of the disengagingmember 2| with the actuating member i3 causes the latter to be cammed away from the shoulder I6 soas to release the rotor. The rotor is thereupon rapidly returned to its normal position by the action of spring 38. During this return movement, the contacts 46, 41 are closed wherebya primary current is generated in the coil 31 by the flux caused to transverse the core 36 thereof by the rotation of the rotor. When the rotor reaches the position shown in Fig. 5 where the change of flux through the core of the coil is at a. maximum, the cam 5| is arranged to be actuated by the coupling element 57 so as to cause disengagement of contacts 46, 41 whereby the primary circuit is broken and the collapse of the field induced thereby causes.

secondary current to be generated for ignition purposes in the usual manner.

Referring to Fig. 6, the curve a illustrates graphically the building up of the. primary current during this workingstroke of the magneto,

and the breaking of the primary circuit at the point I) when the contacts open whereby the current drops to zero.

During the following wind-up stroke of the rotor, if the contacts 46 and 41 are permitted to close at the same point at which they opened, which would be the case if the-cam member 5| were rigidly mounted on the rotor shaft, current would be generated in the coil in a reverse direction as illustrated by the curve 0 in Fig. 6. At the start of the following working stroke, itwill thus be seen that instead of starting from zero, the desired primary current must build up from some negative value such as d whereby the current generated during such working stroke follows the curve e instead of the curve a, and the current value when the contacts open is of some value such as I which is less than the value b by an amount represented by the distance bf. when the oscillation of the magneto rotor is more ill 3 means for generating current by such oscillarapid than about 250 oscillations per minute, it has been found that this loss of efliciency becomes significant as above stated, and increases with increased speed until the operation of the magnet o becomes unsatisfactory.

In order to obviate this difliculty, applicants have provided the lost motion connection between the cam 5i and coupling member 51 whereby the cam 5| remains in its operative position until of its return swing. In this manner, the contacts 46, 41 are held open by the cam 5| until the rotor has traversed the major part of its wind-up stroke so that the primary circuit is open and no reverse currents can be generated therein.

This operation is graphically illustrated in the upper portion of Fig. 6 where the point of closure of the contacts is illustrated at 2', near. the end of the wind-up stroke. The contacts then remain 0 closed throughout the working stroke until the point 7' is reached, whereupon the points open and remain open until the point i is reached on the subsequent wind-up stroke. It has been found in operation that this arrangement efiectually prevents interference with the generation of primary current during the working stroke "so that speeds up to 500 or more oscillations per minute are feasible without perceptible reduction in the efliciency of the magneto. m

Although but one embodiment of. the invention -has been shown and described in detail, it-will be understood that other embodiments arepossible and various changes may be made in the design and arrangements of the parts without departing from the spirit of theinvention as defined in the claims appended hereto.

What is claimed is:

1. In an ignition current generator for internal combustion engines a rotor, meansior oscil- 0 lating said rotor, means whereby rotation of the rotor in one direction causes generation of ignition current, and means for preventing generation of current during most ofthe' rotation of the rotor in the opposite direction.

ing said rotor, means whereby rotation of the rotor in one direction causes generation of current, breaker means for interrupting said current at a. predetermined position of the rotor, and means for preventing closure of said breaker means until the rotor has nearly completed its rotation in the opposite direction.

3. In an ignition magneto for internal combustion engines a rotor, means for oscillating said rotor in timed relation to rotation of'the engine,

means for generating current by such oscillation of the rotor, means for interrupting said current, and a lost motion connection to said rotor for actuating said interrupting means at a predetermined position of the rotor. T

4. In an ignition magneto for internal combustion engines a rotor, means for oscillating said rotor in timed relation to rotation of the engine, means for generating current by such oscillation of the rotor, means for interrupting said current, a lost motion connection to said rotor for actuating said interrupting means at a predetermined position of the rotor, and means for yieldably retaining the interrupting means in its operative and in its inoperative positions.

5. In an ignition magneto for internal combustion engines a rotor, means for oscillating said rotor in timed relation to rotation of the engine,

the rotor has moved through the major portion 2. In an ignition current generator for internal combustion enginesa rotor, means for oscillattion of the rotor, breaker means for interrupting said current, a cam mounted on the rotor for actuating the breaker means, and a lost motion coupling between said rotor and cam constructed and arranged to actuate the cam by the final i movement of the rotor in its oscillation.

6. In an ignition magneto for internal combustion engines a rotor, means for oscillating said rotor in timed relation to rotation of the engine,

means for generating current by such oscillation of the rotor, breaker. means for interrupting said current, a cam mounted on the rotor for actuating the breaker means, a lost motion coupling between said rotor and cam constructed and arranged to actuate the cam by the final movement of the rotor in its oscillation, and means for yieldingly retaining the cam in the positions to which it is moved by the final oscillatory movement of the rotor in either direction.

7. In an ignition, magneto for internal combustion engines a magnetic rotor, yielding means for urging said rotor toward a normal position, coupling means adapted to be operated by an engine for moving said rotor away from normal position, means for disengaging said coupling means at a predetermined point, means including a primary circuit whereby movement of the rotor generates an electric current therein, and means whereby the final movement of the rotor away from normal position closes said circuit, and final return movement of the rotor opens said circuit at a predetermined point.

8. In an ignition magneto for internal combustion engines a magnetic rotor, yielding means for urging said rotor toward a normal position, coupling means adapted to be operated by an engine for moving said rotor away from normal position, means for disengaging said coupling means at a predetermined point, means including a primary circuit whereby movement of the rotor generates an electric current therein, breaker means for opening said circuit, a cam for operating said breaker means, and a lost motion connection for actuating said cam from the rotor.

9. In an ignition magneto for internal combustion engines a magnetic rotor, yielding means for urging said rotor toward a normal position,

coupling, means adapted to be operated by an I engine for moving said rotor away from normal position, means for disengaging said coupling means at a predetermined point, cushioning means. for arresting the return movement of the rotor, means for adjusting said point of disengagement, a primary ignition circuit, and means for closing said circuit shortly before said point of disengagement and for opening said circuit at a. predetermined point shortly before the rotor reaches the end of its Working stroke.

10. An oscillating type ignition magneto for internal combustion engines including a magnetic rotor, a primary electrical circuit including an ignition coil, means whereby'oscillation of the rotor causes magnetic fiux totraverse the core of said coil and induce currents in the coil and primary circuit, means for opening said primary circuit at a time of maximum current flow therethrough, and means for maintaining said circuit open during the subsequent periodof reversal -11. An oscillating type ignition magneto for internal combustion engines including a magnetic rotor, a primary electrical circuit including an ignition coil, means whereby oscillation of the, rotor causes magnetic flux to traverse the core of said coil and ind ce currents in the coil and primary circuit, breaker mechanism for interrupting said circuit, cam means for actuating said breaker, lost motion coupling means between said rotor and cam for causing the cam to open the breaker adjacent one end of a rotor oscillation and allow the breaker to close adjacent the other end of such oscillation, and a. detent for yieldably maintaining the cam in operated position. 

